The proposed research will compare profiles of performance on executive function tasks in individuals with high-functioning autism (HFA), attention-deficit/hyperactivity disorder (ADHD), and schizophrenia, in order to help clarify the underlying cognitive deficit in each. In particular, two key dimensions of executive functions will be studies: working memory and inhibition. This study will directly compare profiles of executive function across these three populations at comparable ages and developmental levels. In addition, verbal working memory, nonverbal working memory, and inhibition will be examined within a single clinical sample, to directly compare different components of executive functions. It is predicted that, compared to matched controls without disabilities (n=20), adults with HFA (n=20) will have working memory impairments, wit verbal working memory showing greater impairments than nonverbal working memory, but inhibition will be intact. Adults with ADHD (n=20) will have intact working memory, but inhibition will be impaired, while adults with schizophrenia will show impairment in both working memory and inhibition. If profile differences are found, the result will provide further evidence that some aspects of executive function are specific to certain disorders.